Transmitting apparatus



P. E. IRELAND TRANSMITTING APPARATUS Oct. 31., 1967 Filed March 24, 1966 INVENTOR. .PAUL E. IRELAND I AGENT.

United States Patent 3,350,031 TRANSMITTING APPARATU Paul E. Ireland, Denver, Colo., assignor to Honeywell Inc., Minneapolis, Minn., a corporation of Delaware Filed Mar. 24, 1966, Ser. No. 537,162 6 Claims. (Cl. 242-156.2)

The invention relates to a control apparatus to main tain the tension in a moving strand, web, or any other similar moving flexible medium at a constant value.

More specifically it is an object of the present invention to provide a constant tension brake for a moving sheet of paper or other thin film as it is unrolled from a spool.

A further object of the invention is to provide a constant brake for a moving sheet of paper, such as chart paper, while it is being transferred from a supply spool to a takeup spool.

A better understanding of the present invention may be had from the following detailed description when read in connection with the accomanying drawings in which:

FIGURE 1 is a view showing the position that the parts of the constant tension brake will be in when a substantially full spool of paper is on the supply spool and FIGURE 2 is a view showing the position the parts of the constant tension brake will be in when nearly all of the paper has been removed from the supply spool.

One of the elements forming the constant tension brake 10 is a yoke 12. This yoke 12 is comprised of two leg portions 14, 16 that are fixedly connected at their lower end to a shaft 18, that in turn is mounted for rotation in bushings 20, 22 that are supported in stationary wall members 24, 26.

Another element that is employed by the brake 10 is a roller pivot member 28. This roller pivot member 28 is comprised of a roller 30 fixedly mounted on a shaft 32 that in turn is mounted for rotation in a bushing 34 of the stationary wall member 24.

A third major element that is employed in the brake 10 is a weight shifting member 36. The member 36 is comprised of a pawl shaped arm 38 that is pivoted to rotate about a stub shaft 40 which in turn is fixedly connected to one leg 42 of an upper U-shaped portion of the yoke 12.

Another part of the brake 10 is an extension spring 44. This spring 44 is connected at its upper end to a stationary member 46 and at its lower end to apply an upward force to the top surface of the arm 38.

A compression spring 50 which is shown extending between the leg 42 of the yoke 12 and an upper portion of the brake arm 52 forms still another portion of the tension brake 10.

The brake arm 52 contains a bushing 54 at its left end to permit the brake arm 52 to be rotatably moved about the shaft 18. The right end of the brake arm 52 contains a brake liner 56 in frictional contact with, 57, the outer cylindrical surface of the disc 58 that forms an integral left end portion of a supply spool 60 which has two flanges 62, 64.

FIGURE 1 shows a full roll of paper 66 wrapped about the spool 60 and an outer portion 68 thereof that is in physical contact with a rotatable guide member 70. This outer portion 68 of the paper 66 is also shown being pulled in the direction of the arrow away from the spool 60 by any paper pulling means such as a motor driven pickup spool, not shown, to which the outer end portion of the paper is attached.

The left end of the guide member 70 has a stub shaft 72 extending therefrom that is supported for rotation in the leg portion 42 of the yoke 12. The right end of the guide member 70 also has a stub shaft, not shown,

that is supported for rotation in the leg portion 74 of the yoke 12 in the same manner as the left end of the guide member 70.

The right end of the spool 60 has a stub shaft protruding therefrom for supporting the spool 60 for rotation in a stationary bushing in the same manner as the stub shaft 76 on the left end of the spool 60.

While the end portion 68 of the paper 66 is being pulled in an upward direction indicated by the arrow from the full supply spool of paper, as shown in FIGURE 1, the portion 80 of the moving paper 66 that extends between the spool 60 and guide member 70 will be in a substantially horizontal position.

While an increasing amount of the paper 66 is pulled from the supply spool 60 and the diameter of the paper 66 on the spool 60 becomes smaller, as shown in FIG- URE 2, the portion 80 of the moving paper 66 extending between the spool 60 and the guide member 70 will gradually be moved from its horizontal position as shown in FIGURE 1 to its inclined position as shown in FIG- URE 2 and the guide member 70 will be simultaneously moved in a counterclockwise direction.

While the counterclockwise movement of the guide member 70 takes place the arm 42 of the yoke 12 that supports the guide member 70 will likewise be moved in a counterclockwise direction from the positon shown in FIGURE 1 to the position shown in FIGURE 2. While this counterclockwise movement of the arm 42 occurs this action will cause the weight shifting member 36 to be simultaneously moved in a clockwise direction about shaft 40 on which it is pivoted due to the sliding contact that takes place between the member 36 and the rotatable roller fulcrum 30 as shown in FIGURE 2.

While this clockwise movement of the weight shifting member 36 occurs the extension spring will be expanded so as to add a progressively increasing force to the weight shifting member 36 and the force per se that the compression spring 50 is permitted to apply to brake arm 52 is progressively decreased.

It can be seen that this change in force acting on pin 40 is brought about because the distance, or moment arm, between the rotatable roller fulcrum 30 and the spring 44 is decreased, and the force of spring 50 on brake arm 52 is decreased during a withdrawal of paper from the supply roll 60. The net result of these spring forces acting on the stub shaft 40 when this counterclockwise rotation of yoke 12 takes place is that a progressively decreasing force will be applied to the stub shaft 40 and a decreasing force will, therefore, be applied to the brake 52 as increasing amounts of paper are removed from the supply spool 60.

The aforementioned linkage 10 thus introduces a unique negative spring rate or a force in the form of friction on the spool 60 that progressively decreases to compensate for the decrease in force due to the moment arm distance between the center of spool 60 and the outer portion 80 of the paper 68 decreasing While the paper 68 is removed from the spool 60.

From the aforementioned description of the linkage 10 it can, therefore, be seen that this linkage provides a means for maintaining constant tension in a piece of paper or other thin film or moving medium as it is being pulled off a spool of paper and the diameter of the roll thereon is being progressively decreased.

What is claimed is:

1. An apparatus to maintain a constant tension in a moving flexible medium being unspooled from a rotatable spool, comprising a roller in contact with a portion of the flexible medium that has been unspooled, a link operably connected to support the roller for arcuate movement about a stationary pivot means as the unspooling of the flexible medium takes place, an arm pivotedly connected to the link, a stationary stub shaft, a rotatable fulcrum mounted for rotation on the stub shaft, a first spring extending between a stationary member and the arm to retain the arm in slidable contact with the rotatable fulcrum as the arcuate movement of the link takes place, a brake arm to apply friction to the spool, and a second spring extending between the link and the brake arm to alter the amount of the friction that the brake arm applies to the end of the 'spool as the arcuate movement of the link takes place. I

2. The apparatus defined in claim 1 wherein the first spring is an extension spring and the second spring is a compression spring.

3. The apparatus defined in claim 1 wherein the brake arm is mounted for arcuate movement about the pivot means on which the link is mounted.

4. The apparatus as defined in claim 1 wherein the arm is of such a characteristically shaped configuration that the portion of the first spring connected to the arm will be moved by the arm toward the rotatable fulcrum member when the arcuate movement of the roller occurs during the unspooling of the flexible medium from the rotatable spool.

5. The apparatus defined in claim 1 wherein the arm is of such a characteristically shaped configuration that the portion of the first spring connected to the arm will be moved by the arm toward the rotatable fulcrum member and the second spring is positioned on the link for movement therewith to reduce the amount of friction being applied by the second spring to the brake arm when arcuate movement of the roller occurs during unspooling of the flexible medium from the rotatable spool.

6. The apparatus defined in claim 1 wherein the first spring is an extension spring and the second spring is a compression spring, and wherein the arm is of such a characteristically shaped configuration that the portion of the extension spring connected to the arm will be moved by the arm toward the rotatable fulcrum member and the compression spring is positioned on the link for movement therewith to reduce the amount of friction being applied by the compression spring to the brake arm when arcuate movement of the roller occurs during unspooling of the flexible medium from the rotatable spool.

References Cited UNITED STATES PATENTS 1,671,976 6/1928 Avery 242l56.2 2,215,651 9/1940 Pierce 242-1562 X 2,419,808 4/1947 Wirth 242 156.2 3,111,742 1/1964 Trombetta 242-1562 FOREIGN PATENTS 793,404 11/1935 France.

STANLEY N. GILREATH, Primary Examiner; 

1. AN APPARATUS TO MAINTAIN A CONSTANT TENSION IN A MOVING FLEXIBLE MEDIUM BEING UNSPOOLED FROM A ROTATABLE SPOOL, COMPRISING A ROLLER IN CONTACT WITH A PORTION OF THE FLEXIBLE MEDIUM THAT HAS BEEN UNSPOOLED, A LINK OPERABLY CONNECTED TO SUPPORT THE ROLLER FOR ARCUATE MOVEMENT ABOUT A STATIONARY PIVOT MEANS AS THE UNSPOOLING OF THE FLEXIBLE MEDIUM TAKES PLACE, AN ARM PIVOTEDLY CONNECTED TO THE LINK, A STATIONARY STUB SHAFT, A ROTATABLE FULCRUM MOUNTED FOR ROTATION ON THE STUB SHAFT, A ROTATABLE SPRING EXTENDING BETWEEN A STATIONARY MEMBER AND THE ARM TO RETAIN THE ARM IN SLIDABLE CONTACT WITH THE ROTATABLE FULCRUM AS THE ARCUATE MOVEMENT OF THE LINK TAKES PLACE, A BRAKE ARM TO APPLY FRICTION TO THE SPOOL, AND A SECOND SPRING EXTENDING BETWEEN THE LINK AND THE BRAKE ARM TO ALTER THE AMOUNT OF THE FRICTION THAT THE BRAKE ARM APPLIES TO THE END OF THE SPOOL AS THE ARCUATE MOVEMENT OF THE LINK TAKES PLACE. 